Automatic leveling telescope including a reversible two-sided pendulum mirror and a focusing prism

ABSTRACT

A telescope having an optical axis comprising a housing with a light entrance aperture having a geometrical axis, an objective mounted in the aperture, the optical axis of the objective being parallel to the geometrical axis, a set of two prisms disposed in the housing near the objective, the objective and one of the prisms being jointly movable in a direction at a right angle to the optical axis, a collimating mark disposed on the one prism and movable therewith, focusing means comprising a rectangular prism mounted in the housing at an end thereof remote from the aperture, with the hypotenuse surface facing the objective, the rectangular prism being displaceable along the optical axis to focus on the collimating mark imaging rays traversing the objective, a pendulum mirror disposed in the housing in the path of imaging rays deflected by the rectangular prism, the mirror having a silvered surface in front and in the rear and being suspended for oscillation, said mirror being rotatable between a first and a second position about an axis of rotation substantially at a right angle to the optical axis for automatically leveling the sighting of the telescope, rotating means for rotating the mirror between the first and the second position, damping means for damping the oscillation of the mirror, one of the silvered surfaces cooperating with the objective when the mirror is in the first position and the other of the silvered surfaces cooperating with the objective when the mirror is in the second position, an eyepiece mounted on one end of the housing remote from the aperture for viewing the collimating mark, the one prism of the set of prisms deviating the collimary ray in the telescope at a right angle to the optical axis of the objective, the other of the set of prisms deviating the collimary ray to be parallel with the optical axis of the eyepiece, and lens means located between the other of the set of prisms and the eyepiece for producing an intermediate image.

United States Patent [72] Inventor Gerhard Hiither Jena, Germany 2 1]App]. No. $7,320 121 FEE! i- ,w. n. [23] Division of Ser. No. 788,668,Oct. 17, 1968,

v fi 9-. 5 [45] Patented Oct. 5, 1971 [7 3] Assignee VEB Carl Zeiss leaatkaefisre Germany a which is a continuation of iigllcatign Ser. No.405,334, Oct. 19, 1964, now abandoned.

[54] AUTOMATIC LEVELING TELESCOPE INCLUDING A REVERSIBLE TWO-SIDEDPENDULUM MIRROR AND A F OCUSING PRISM 2 Claims, 5 Drawing Figs.

52 us. Cl 356/250, 350/10, 350/16 [51] Int. Cl G0lc 9/12 [50] Field ofSearch 350/16, 47, 50, 10; 356/149, 250

[56] References Cited UNITED STATES PATENTS 2,189,766 2/1940 Unertl350/10 X 2,638,032 5/1953 Kieffer et al. 350/47 2,907,246 10/1959Far-rand et al. 356/250 2,978,950 4/1961 Mandler 356/153 3,059,520[0/1962 Tsubokawa 356/250 FOREIGN PATENTS 355,230 10/1905 France PrimaryExaminer-David H. Rubin Attorney-Nolte and Nolte ABSTRACT: A telescopehaving an optical axis comprising a housing with a light entranceaperture having a geometrical axis, an objective mounted in theaperture, the optical axis of the objective being parallel to thegeometrical axis, a set of two prisms disposed in the housing near theobjective, the objective and one of the prisms being jointly movable ina direction at a right angle to the optical axis, a collimating markdisposed on the one prism and movable therewith, focusing meanscomprising a rectangular prism mounted in the housing at an end thereofremote from the aperture, with the hypotenuse surface facing theobjective, the rectangular prism being displaceable along the opticalaxis to focus on the collimating mark imaging rays traversing theobjective, a pendulum mirror disposed in the housing in the path ofimaging rays deflected by the rectangular prism, the mirror having asilvered surface in front and in the rear and being suspended foroscillation, said mirror being rotatable between a first and a secondposition about an axis of rotation substantially at a right angle to theoptical axis for automatically leveling the sighting of the telescope,rotating means for rotating the mirror between the first and the secondposition, damping means for damping the oscillation of the mirror, oneof the silvered surfaces cooperating with the objective when the mirroris in the first position and the other of the silvered surfacescooperating with the objective when the mirror is in the secondposition, an eyepiece mounted on one end of the housing remote from theaperture for viewing the collimating mark, the one prism of the set ofprisms deviating the collimary ray in the telescope at a right angle tothe optical axis of the objective, the other of the set of prismsdeviating the collimary ray to be parallel with the optical axis of theeyepiece, and lens means located between the other of the set of prismsand the eyepiece for producing an intermediate image.

AUTOMATIC LEVELING TELESCOPE INCLUDING A REVERSIBLE TWO-SIDED PENDULUMMIRROR AND A FOCUSING PRISM This is a division of Ser. No. 788,668,filed Oct. 17, I968, now Pat. No. 3,552,866 issued Jan. 5, 1971, which,in turn, is a continuation of Ser. No. 405,334, filed Oct. 19, I964.

The present invention relates to measuring or sighting telescopes whichhave a collimating mark carrier and an automatic sighting line controland which can be used particularly for geodetic and precision measuringinstruments.

The precision and reliability of the measuring results depend largely onthe adjusting accuracy and stability of the means influencingthesighting line, especially on that of the objective, the collimating markcarrier and not least the sighting line control. The position of thesighting line can be checked by suitable test methods and means, anddetected divergences can with more or less precision be correctedaccording to the adjusting possibilities at disposal, but the operatorwill generally have to put up with a certain residual error. Moreover,in the hitherto known measuring and testing telescopes it is unavoidableand very disadvantageous that thermal and mechanical influencesinterfere with the means controlling the sighting line. Tests andreadjustments repeated from time to time cannot satisfactorily cope withthis phenomenon, it being necessary to pay particular attention to themethodical principles of precision measuring. Precision leveling, forexample, requires that sightings in a definite sequence according to adefinite scheme take place with due regard to equal sighting distancesforward and backward. Carrying such methodical principles into practiceis a severe handicap on both the economy and the precision of themeasuring process.

The present invention aims at overcoming the forgoing disadvantages andhas for an object the provision of a measuring or sighting telescope inwhich the sighting line is very stable and accurate and in which thecost of and the time taken by the measures making for and guaranteeinghigh precision remain within strictly economic limits.

To this end, the present invention consists in a measuring or sightingtelescope having a collimating mark carrier and an automatic sightingline control, characterized in that the collimating mark carrier and thetelescope objective can be rotated at least 180 about an axis parallelto the optical telescope axis and/or that the sighting line control canbe rotated 180 about a stationary axis which coincides approximatelywith the plumb line containing the locus of the instrument. In thistelescope, two independent measuring values in extreme positions areobtained which have the same but opposite errors, and the mean of whichis the accurate value, in analogy with the mean value obtained byobservation through two telescopes set up at different places. Precisionleveling, in particular, is thus possible without forward stationing andwithout strict equality of the sighting distances, the consequence beinggreat operational economy and, because of the cutting of the timerequired for precision leveling, increased measuring accuracy andreliability.

A particularly simple embodiment of the invention is a telescope havinga collimating markon its objective and a sighting line control at halfthe image distance. If this sighting line control is a pendulum mirror,this mirror must have two parallel reflecting surfaces. The telescope isparticularly suitable for high precision work if the collimating mark inthe rear nodal plane is rigidly connected to the objective and if thereare no means influencing the ray path between objective and sightingline control.

In a further embodiment of the invention, the telescope is particularlyeasy to handle by a driving means which rotates the objective andcollimating mark and also the sighting line control.

Precision sighting telescopes generally have an optical micrometercomprising plane-parallel plates or optical sliding wedges. According toa still further embodiment of the invention, the sighting or measuringtelescope has only a simple micrometer, the objective and collimatingmark carrier being displaceable at right angles to the optical axis.

In order that the invention may be more readily understood, reference ismade to the accompanying drawing which illustrates diagrammatically andby way of example three embodiments thereof, and in which:

FIG. 1 shows one embodiment in longitudinal section;

FIGS. 2 and 3 show another embodiment in longitudinal and cross section,respectively;

FIG. 4 shows a third embodiment in longitudinal section, and

FIG. 5 shows the bearing of a sighting-line control.

In FIG. 1, housing 1 contains an optical system comprising an objective2, a focusing lens 3, a pendulum mirror 4, two right-angled prisms 5 and6, two optical imaging elements 7 and 8, and an eyepiece 9. The axis X,Xof the optical system is a deviated axis. The housing I has a window 10in the form of an optical adjustment wedge, which serves aslight-entrance aperture.

Bearings ll, l2, l3 and 14 in the housing I carry a tubelS whichcontains the objective 2 and the focusing lens 3. The tube 15 isrotatable about its geometric axis, which coincides at leastapproximately with the part of the optical axis X,-X traversing theobjective 2. The rear side of the objective 2 bears a collimating mark16 which is as close as possible to the optical axis, and the focusinglens 3 is displaceable along the optical axis X,-X,. The end of the tube15 remote from the objective 2 is fixed to a bevel gear 17 which engagesa bevel gear 19. By means of a milled head 18 outside the housing 1 thegear 19 is rotatable about an axis L,-L,. When the sighting line controlis in zero position, the axis L -L coincides approximately with theplumb line containing the locus of the instrument. On the lower part ofthe cylindrical surface of the milled head 18 are adjustment marks 20cooperating with an index 21 fixed to the housing I. The bevel gear 19by means of strings 23 suspends a pendulum 22 carrying the pendulummirror 4 which is plane and has on either side reflecting surfaces 25and 26, respectively. The oscillations of the pendulum 22 are influencedby damping means (not shown).

The prism 5 is connected to the housing 1 by arms 27. The prism 6, thetwo optical elements 7 and 8, which produce an intermediate image, andthe eyepiece 9 are also fixed to the housing 1.

A light beam proceeding from a target traverses the window 10 and bymeans of the objective 2 and the focusing lens 3 and after reflection onthe pendulum mirror 4 images the target in the plane of the collimatingmark 16. This image by way of the rectangular deviating prism 6 and theoptical elements 7 and 8 is projected in the image plane of the eyepiece9.

When using the telescope, each target is aimed at twice. Between thesetwo sightings, the mirror 4 is so rotated by turning the head 18 throughl that the reflecting surface 26 becomes available for the secondsighting, the reflecting surface 25 having been employed in the firstsighting. Any fault in the adjustment sightings being equal to eachcompensated, the errors in the two aimings being equal to each other.Turning the head 18 through causes the bevel gears 19 and 17 to rotateby 180 the tube 15 containing the objective 2. Accordingly, theinfluences of slight eccentricities of the collimating mark 16 relativeto the optical axis X,-X,, as well as effects of errors of the sightingline control on the measurement can be eliminated by averaging theresults of the two sightings.

FIGS. 2 and 3 show a housing 31 having a window 30 and containing anoptical system which is similar to the system shown in FIG. I. Thesystem in the housing 31 has an optical axis X,-X, and comprises anobjective 32, a collimating mark 33 thereon, a pendulum mirror 34, tworectangular prisms 35 and 36, two optical elements 37 and 38 producingan intermediate image, and an eyepiece 39. The prism 35 is cemented tothe window 30, which is a transparent plane-parallel plate, the centerof the hypotenuse surface of the prism 35 lying in ,the optical axis X-X which also contains the collimating mark 33.

The objective 32 is rigidly mounted in a tube 40 containing grooves 41and 42 which guide a tube 44 fixed to a bevel gear 43 and displaceableagainst the pressure of springs 47 and 48 resting on stops 45 and 46fixed to the tube 40. The bevel gear 43 engages a bevel gear 49 which ismounted in the housing 31 and is rotatable by means of a milled head 50.The bevel gear 49 by means of tapes 53 suspends a mirror 34 having twoplane-parallel reflecting surfaces 51 and 52. The pendulum minor 34 hasa damping device which consists of a piston 54 and a cylinder 55 andwhich by means of walls 56 and 57 is rigidly connected to the bevel gear49. The lower ends of the walls 56 and 57 are interconnected by acircular plate 64 which is embedded in a guide comprising two guiderails 65 and 66 fixed to the housing 31.

To the exterior sides of the walls 56 and 57 are fixed racks 58 and 59parallel to the optical axis X,-X,. A pinion 60 mounted in the housing31 and in connection with a hand wheel 61 rotates together with a shaft62 and under the pressure of a spring 63 engages one of the two racks 58and 59, the engagements in FIGS. 2 and 3 being with rack 58.

As in FIG. 1, the parallel rays of a light beam entering the objective32 and deflected by the mirror 34 are united in the rear nodal plane ofthe objective, which contains the collimating mark 33. The prisms 35 and36 and the optical elements 37 and 38 project an image of the target inthe image plane of the eyepiece 39.

The telescope is operated as follows: It is focused by rotating the handwheel 61, so that the bevel gear 49 together with the pendulum mirror 34and the damping means 54 and 55 are displaced along the guide rails 65and 66, and the tube 40 along the grooves 41 and 42, an oblong hole 67in the housing 31 allowing the milled head 50 fixed to the bevel gear 49to take part in this displacement. To protect the measurement from beinginfluenced by errors due to deviation of the collimating mark 33 fromthe optical axis X -X and to dislocation of the pendulum mirror 34, thetelescope objective 32 and the pendulum mirror 34 after a first aimingby means of the reflecting surface 51 are rotated 180, and the samepoint is then aimed at by means of the reflecting surface 52. To thisend, the wheel 61 is disengaged from the pinion 60 against the action ofthe spring 63, and the bevel gear 49 together with the pendulum mirror34 and the damping means 54 and 55 are rotated to make the pinion 60engage the rack 59.

Focusing is possible also by means of the objective 32, the pendulummirror 34 remaining stationary.

The embodiment shown in FIGS. 2 and 3 is particularly advantageousbecause the space between objective and sighting line control andcollimating mark are without any means influencing the ray path.

The embodiment of FIG. 4 comprises a housing 70, an objective 71, arectangular prism 72, a pendulum mirror 73, two rectangular prisms 74and 75, two optical imaging elements 76 and 77, and an eyepiece 78. Themount 79 of the objective 71 is measurably displaceable in guides 80 inthe housing 70. Parallel to the optical axis X,X,, the prism 72 isdisplaceable along guides 81 in the housing 70 by means of a nut 83fixed to a hand wheel 82 and a spindle 85 fixed to the prism mount 84. Aspring 86 around the spindle 85 prevents backlash between the nut 83 andthe spindle 85.

In the housing 70 is rotatably mounted a base 87 suspending a pendulum88 and pendulum mirror 73 by means of crossedtapes spring joints 89.Rotation of the pendulum 88 about its axis; which coincides at leastapproximately with the plumb line L -L,, is effected by means of amilled head 92. The head 92 has two stop pins 90 and 91, so that itsrotation can be interrupted by a stop 93 fixed to the housing 70. Therectangular prism 74 bears a collimating mark 94 on its hypotenusesurface and is cemented to the rear of the objective 71.

The telescope is operated as follows: it is focused by means of theprism 72. The pin 90 is given the position in which it contacts the stop93, and the target (not shown) is aimed at. Slight vertical deviationsof the collimating mark from the taret point in the image can berectified by vertically displacing t e ob ective in its guides (thedisplacing means being omitted in the drawing). Consequent lack ofdefinition in the image plane of the eyepiece is overcome for example bydisplacement of the optical imaging element 76. Subsequently thereto,the pendulum mirror 73 is rotated 180, so that the pin 91 comes incontact with the stop 93 and the other reflecting surface of thependulum mirror 73 faces the hypotenuse surface of the prism 72. Ifnecessary, the objective 71 can be vertically displaced.

The arrangement of the ray paths in the embodiment of FIG. 4 providesthe advantage of a very compact telescope.

The pendulum mirrors and their suspension, shown very schematically inFIGS. 1 to 4, are represented in detail in FIG. 5: A carrier 98 ismounted for rotation about the axis L -L on balls 96 and 97 running on abaseplate 95. The carrier 98 supports two pendulum bearings 99 and 100,a pendulum 101 in the form of a piston, and a damping cylinder 109. Thependulum bearings 99 and are screwed to the carrier 98 and a bevel gear102. The head 104 by means of a click-stop 105 can be held in twopositions displaced relatively to each other. A pendulum mirror 106connected to the piston 101 has trunnions 107 and 108 rotatable in thebearings 99 and 100.

The constructional examples shown in the drawings do not exhaust theidea underlying the invention, which is by no means restricted to anyparticular kind of sighting line control or telescope. The pendulum canbe a suspended or an inverted one. The optical construction permitssingle or multiple reflections on the oscillating and stationary opticalelements. The telescope itself can be of the angular or thestraight-vision type.

What is claimed is:

1. A telescope having an optical axis comprising a housing with a lightentrance aperture having a geometrical axis, an objective mounted insaid aperture, the optical axis of said objective being parallel to saidgeometrical axis, a set of two prisms disposed in said housing near saidobjective, said objective and one of said prisms being mounted for jointmovement in a direction at a right angle to said optical axis, acollimating mark disposed on said one prism and movable therewith,focusing means comprising a rectangular prism movably mounted in saidhousing at an end thereof remote from said aperture, with the hypotenusesurface facing said objective, said rectangular prism being displaceablealong said optical axis to focus on said collimating mark imaging raystraversing said objective, a pendulum mirror disposed in said housing inthe path of imaging rays deflected by said rectangular prism, saidmirror having a silvered surface in front and in the rear and beingsuspended for oscillation, said mirror being rotatable between a firstand a second position about an axis of rotation substantially at a rightangle to said optical axis for automatically leveling the sighting lineof the telescope, rotating means for rotating said mirror between saidfirst and said second position, damping means for damping theoscillation of said mirror, one of said silvered surfaces cooperatingwith said objective when said mirror is in said first position and theother of said silvered surfaces cooperating with said objective whensaid mirror is in said second position, an eyepiece mounted on one endof said housing remote from said aperture for viewing said collimatingmark, said one of the prisms of said set of prisms deviating the image.and collimating mark rays in the telescope at a right angle to theoptical axis of the objective, the other of said set of prisms deviatingthe image and collimating mark rays to be parallel with the optical axisof said eyepiece, and lens means located between the other of said setof prisms and said eyepiece for producing an intermediate image.

2. A telescope as set forth in claim 1, also comprising externallyoperable control means for controlling the movement of said rectangularprism along said optical axis.

1. A telescope having an optical axis comprising a housing with a lightentrance aperture having a geometrical axis, an objective mounted insaid aperture, the optical axis of said objective being parallel to saidgeometrical axis, a set of two prisms disposed in said housing near saidobjective, said objective and one of said prisms being mounted for jointmovement in a direction at a right angle to said optical axis, acollimating mark disposed on said one prism and movable therewith,focusing means comprising a rectangular prism movably mounted in saidhousing at an end thereof remote from said aperture, with the hypotenusesurface facing said objective, said rectangular prism being displaceablealong said optical axis to focus on said collimating mark imaging raystraversing said objective, a pendulum mirror disposed in said housing inthe path of imaging rays deflected by said rectangular prism, saidmirror having a silvered surface in front and in the rear and beingsuspended for oscillation, said mirror being rotatable between a firstand a second position about an axis of rotation substantially at a rightangle to said optical axis for automatically leveling the sighting lineof the telescope, rotating means for rotating said mirror between saidfirst and said second position, damping means for damping theoscillation of said mirror, one of said silvered surfaces cooperatingwith said objective when said mirror is in said first position and theother of said silvered surfaces cooperating with said objective whensaid mirror is in said second position, an eyepiece mounted on one endof said housing remote from said aperture for viewing said collimatingmark, said one of the prisms of said set of prisms deviating the imageand collimating mark rays in the telescope at a right angle to theoptical axis of the objective, the other of said set of prisms deviatingthe image and collimating mark rays to be parallel with the optical axisof said eyepiece, and lens means located between the other of said setof prisms and said eyepiece for producing an intermediate image.
 2. Atelescope as set forth in claim 1, also comprising externally operablecontrol means for controlling the movement of said rectangular prismalong said optical axis.